This application relates to and claims priority from Japanese Patent Application Nos. 10-369090 filed on Dec. 25, 1998 and 11-284746 filed on Oct. 5, 1999, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates generally to a vehicle air conditioner, and particularly to an air passage of an air conditioning unit in which a heater core is disposed in a substantially horizontal direction.
2. Related Art
JP-A-9-123748 discloses a vehicle air conditioner in which a heater core is disposed in a substantially horizontal direction. As shown in FIG. 4, the air conditioning unit has a case 50 and a warm air guide 110 for guiding warm air heated by a heater core 100 to a downstream air side. The case 50 has a face opening 120, a defroster opening 130 and a foot opening 140 provided above the warm air guide 110. Each of the openings 120, 130 and 140 communicates with an air outlet formed in a passenger compartment of a vehicle, and is selectively opened and closed by a face door 150 and a defroster door 160. When the face door 150 fully opens the face opening 120, an air port 170 through which air flows toward the defroster opening 130 and the foot opening 140 is closed. When the face door 150 fully opens the air port 170, the face opening 120 is closed.
The air port 170 is disposed at an upstream air side of the defroster opening 130 and the foot opening 140. Therefore, when a defroster air mode or the like is selected, air is introduced into the defroster opening 130 through the air port 170. However, since the air port 170 is opened and closed by the face door 150, a sealing wall portion 180 needs to be formed to extend from the warm air guide 110 to the case 50, so that a peripheral portion of the face door 150 contacts the sealing wall portion 180 for sealing when the face door 150 closes the air port 170. Therefore, an opening area of the air port 170 is decreased due to the sealing wall portion 180. As a result, an amount of air flowing into the defroster opening 130 is decreased, and a windshield of the vehicle may be fogged.
Further, as shown in FIG. 5A, when the face opening 120 has a center face opening 120a and a side face opening 120b, and the side face opening 12b is constantly open so that side windows of the vehicle are sufficiently defrosted, the face door 150 only opens and closes the center face opening 120a. Therefore, a width of the face door 150 (i.e., a length of the face door 150 in a right-left direction in FIG. 5A) is decreased from that of the face door 150 which opens and closes both the center face opening 120a and the side face opening 120b. As a result, as shown in FIG. 5B, a width of the air port 170 is decreased corresponding to the width of the face door 150, thereby further decreasing an opening area of the air port 170. As a result, an amount of air introduced into the defroster opening 130 is further decreased.
The opening area of the air port 170 may be simply increased by increasing the width of the air port 170 or a height of the air port 170 (i.e., a length of the air port 170 in a vertical direction in FIG. 5B). However, when the width of the air port 170 is increased, a width of the vehicle air conditioner is increased. When the height of the air port 170 is increased by enlarging the air port 170 upwardly, a height of the vehicle air conditioner is increased. When the height of the air port 170 is increased by enlarging the air port 170 downwardly, the warm air guide 110 may need to be moved downwardly. When the warm air guide 110 is moved downwardly, a warm air passage 190 formed between the warm air guide 110 and the heater core 100 is narrowed, thereby increasing flow resistance in the warm air passage 190. As a result, an amount of warm air flowing through the warm air passage 190 is decreased, and an amount of air introduced into the defroster opening 130 is decreased.
In view of the foregoing problems, it is an object of the present invention to provide a vehicle air conditioner which has a sufficient amount of air blown from a defroster air outlet without increasing a size of an air conditioning unit.
According to the present invention, a vehicle air conditioner has a case for forming an air passage, a heating heat exchanger disposed in the case in a substantially horizontal direction for heating air, a warm air guide disposed above the heating heat exchanger for guiding air heated by the heating heat exchanger and a switching door. The case has a first air opening and a second air opening through which air flows in different directions. The air passage includes an air port disposed at an upstream air side of the second air opening. Warm air passing through the heating heat exchanger is guided by the warm air guide into an air mixing space in which the warm air is mixed with cool air bypassing the heating heat exchanger. The air mixing space is formed next to the heating heat exchanger in a vehicle front-rear direction in the air passage. The warm air guide is disposed at a substantially same height as the air port, and has an end portion for defining the air port. The switching door selectively opens and closes the first air opening and the air port, and has an end portion which contacts the end portion of the warm air guide to close the air port.
As a result, an opening area of the air port is readily increased by decreasing a length of the warm air guide in the vehicle front-rear direction, and a sealing wall portion extending from the warm air guide to the case to contact the switching door is not required. Therefore, an amount of air flowing through the air port is increased without increasing a size of the air conditioner, and an amount of air flowing into the second air opening is increased.